Development and analysis of the processing of hybrid textiles into endless-fibre-reinforced thermoplastic composites

This thesis contributes to an acceleration of the manufacturing process of composite components from hybrid textiles, which contain reinforcement fibres and polymer matrix fibres from high-performance thermoplastics. Hybrid textiles distinguish in terms of drapeability compared to thermoplastic tapes. A comprehensive material characterisation of two polyetheretherketone polymers and different configurations of hybrid textiles deliver input parameters for a consolidation model. This model comprises the process steps of heating, impregnation and cooling, with a focus laying on the knowledge-based description of impregnation on meso-scale.

Relevant process parameters are investigated on model scale to support the development of the Isoforming process, which is a new developed thermoforming process tailored for hybrid textiles. During the process, the steps of heating and cooling are accelerated remarkably compared to classic variothermal approaches.

A subsequent sensitivity analysis validates the consolidation model. Beside the applied pressure and impregnation time, the textile configuration is a governing factor, which is analysed to recommend parameters for a successful consolidation process. Furthermore, a comparison between porosity and resulting mechanical parameters delivers information about the recommendable maximum values of void contents in laminates. Finally, a process analysis, which comprises online thickness assessment, laminate-embedded fibre-optic sensors and a transparent tooling, provides information about the feasibility of an online assessment of the state of impregnation.